The present invention relates generally to optical security coatings for protection of a print and/or object, and is particularly concerned with a removable optical security coating applied to a substrate in order to totally or completely hide confidential information printed on the substrate and to authenticate the information, and to a method of making such an optical security device.
Currently, there exists in the market a series of printed documents such as calling cards, instant lottery tickets, promotions, licenses, event tickets, and similar items, which contain information, activation codes, prizes, etc. hidden by means of a removable material. The purpose of the removable material is to ensure the confidentiality of the code or message printed under the material before it is acquired by the final consumer. However, a problem faced by this type of application of removable material on products is the possibility that, after the removable material is removed from the surface and the hidden information is used, the document is then discarded by the user. The discarded document, which no longer has any commercial value, can be picked up and reused illegally, by reapplying the removable material, typically a gray scratch-off coating, in order to sell the document as new. Additionally, the document can be re-printed in any conventional printing method to imitate the original, since both the original and the gray coating can be readily imitated.
To date, there is no security measure which would indicate the reprocessing or duplication of such documents which have already been used, and the authenticity of such documents cannot be checked. Thus, users who purchase these reprocessed documents suffer an economic loss, and the manufacturers or issuers suffer damage to their image, in addition to economic losses.
The current technique involves the application of a removable material to a smooth surface by conventional printing methods such as flexography, serigraphy, offset, rotagravure, hot stamping, and the like. However, the removable material does not have any security measures or elements to identify reprocessed or duplicated documents, so any printer may easily reapply the film or copy the print with the film by conventional printing methods.
It is an object of the present invention to provide a new and improved optical security article and method.
According to one aspect of the present invention, an optical security article is provided, which comprises a substrate carrying printed information and an optical security coating removably applied over the information on the substrate, the optical security coating having engraved optical elements and having an adhesive component for adhesively securing the coating to the substrate, the adhesive component having a predetermined adherence strength for resisting accidental removal of the coating from the substrate by frictional forces, and permitting complete removal of the coating from the substrate by scratching or scraping it off the substrate without damaging or altering the printed information on the substrate.
The optical security coating has optical elements having characteristics which cannot be duplicated by conventional printing methods, and can be applied or transferred to the substrate by any traditional or non-traditional method, such as hot stamping, cold foil transfer, a UV lacquer process, or the like.
The optical security coating has a predetermined balance between adhesion strength and removal strength such that it will not be removed accidentally, but can be readily scratched or scraped off by a user without damage to the underlying printed information.
The removable optical security coating will authenticate and validate the confidential information previously printed on the underlying surface. In addition to the optical security characteristics, the optical security coating also has the correct balance between adhesion strength and frictional removal strength, which gives it additional characteristics as a security element preventing reprocessing of documents already used. The optical coating may include any type of optical elements that give consumers confidence that the article has not been reused or duplicated, and therefore that the hidden information has not been seen or used by anyone else, thus ensuring its confidentiality.
The optical security coating may be opaque or transparent. The purpose of an opaque optical security coating is to hide the underlying information, which may be a prize code, for example. A transparent optical security coating may be used to validate the visible information, since, by removing the coating, an optical effect validating the underlying information may appear.
The optical coating may be only partially removed in some cases. The printed information, together with permanent parts of the coating (after the coating is removed) may give a correct code in order to validate the printed information.
According to another aspect of the present invention, a method of applying a security coating to a substrate is provided, which comprises transfer of a coating containing an optical image onto a substrate in order to at least partially cover printed information on the substate using a transfer printing process, such that the coating is removably adhered to the substrate with sufficient adhesion strength to resist any accidental peeling off of the coating, and is completely removable from the underlying substrate without altering or damaging the substrate by scratching or scraping off the coating from the substrate.
The coating may be transferred onto the substrate by a transfer printing process selected from the group consisting of flexography, serigraphy, offset, rotogravure, labeling, hot stamping, cold foil, or UV lacquer. Optical elements are engraved microscopically into the coating either prior to or after tansfer onto the substrate, and the optical elements are selected from the group consisting of holograms, diffraction gradients, optically variable diffraction elements (OVD), dot matrix elements, computer generated holograms, stereograms, hexelgrams, and kinegrams.
After transfer onto the substrate, the optical security coating can only be removed by scratching or scraping it from the substrate, and is designed to be released without damaging the substrate or leaving any residue on the substrate. However, after removal of the coating to reveal the information underneath, the coating cannot be reproduced in any attempt to duplicate the original article or re-apply a coating to the article after use. This is because the coating contains optical security information which cannot be reproduced.
This invention involves an optical security coating that can be applied by any printing method known in the field, such as flexography, serigraphy, offset, rotogravure, labeling, hot stamping, and the like, but with the additional step of engraving optical elements into the coating , so as to provide security to the document or surface to which the coating is applied. The removable coating has optical characteristics that prevent the illicit reuse or reprocessing of the substrate to which it is initially applied, giving the final user security that the information contained in the document has been kept confidential.
The optical coating may be totally or partially removed, showing that the printed information has already been used, thus offering a security element by which the user can easily and fully identify the article as original.
The term xe2x80x9coptical coatingxe2x80x9d as used herein refers to the microscopic engraving of any optical element on a coating or transfer material. The optical elements that may be engraved microscopically on a coating can be, without limitation thereto, holograms, diffraction elements, optically variable diffraction elements (OVD), dot matrix elements (at any resolution), computer-generated holograms, stereograms, hexelgrams, kinegrams, and the like. This type of optical element generates optical reliefs, and cannot be easily circumvented or duplicated without authorization.
It must be understood that the incorporation of the optical element or elements is not limited to the aforementioned interference patterns; it may be extrapolated to produce optical elements in the volume of the coating by the well-known system used to generate holograms and/or optical reflection elements.
The type of information protected by the removable optical security coating may be, for example, activation codes, prizes, lottery numbers, codes, logos, photographs, numbers, and the like. This confidential information is contained in printed documents such as calling cards, instant lottery tickets, promotions, licenses, collectible cards, event tickets, and similar documents.
Generally speaking, this invention""s removable optical coating includes both the temporary application of a removable material with adhesive characteristics on the substrate to which it is applied, and the engraving of optical elements onto the removable material. In this sense, the correct balance will be achieved if the removable material and optical elements of the coating resist the friction forces generated, for example, during packing, distribution, and exhibition of the article, and similar actions, when handling the article to which the optical security coating is applied. At the same time, the optical coating can be easily removed to see the information underneath, by scratching or scraping off the coating. Thus, excessive adherence strength of the removable material would cause the destruction of the base or printed information when trying to remove the coating which contains a security measure to prevent reading of the information. Insufficient adherence strength would make the removable coating peel off when the product is handled, thus making the product unusable, because the hidden information would be exposed.
The removable optical security coating is normally opaque to hide the printed information under the coating. However, it may be transparent. In one embodiment of the invention, the coating is opaque in order to hide all the information found under the security coating. In an alternative embodiment, a transparent optical coating is used to validate the visible information under the coating when, after removing the coating, an optical effect validating the information underneath finally appears. In this case, a transparent optical security coating will validate the information when it is under a transparent removable coating with the same refraction index. By removing the transparent removable coating, the optical security effect engraved underneath on the other fixed, transparent coating will be activated, validating the information printed on the object or document.